Electrical conduction behavior of La, Co co-doped SrTiO3 perovskite as anode material for solid oxide fuel cells

The effects of La- and Co-doping into SrTiO3 perovskite oxides on their phase structure, electrical conductivity, ionic conductivity and oxygen vacancy concentration have been investigated. The solid solution limits of La in LaxSr1-xTiO3 (-) (delta) and Co in La0.3Sr0.7Coy Ti1-yO3 - delta are about 40 mol% and 7 mol%, respectively, at 1500 degrees C. The incorporation of La decreases the band gap and thus increases the electrical conductivity of SrTiO3 remarkably. La0.3Sr0.7TiO3 - delta shows an electrical conductivity of 247 S/cm at 700 degrees C. Co-doping into La0.3Sr0.7TiO3 - delta increases the oxygen vacancy concentration and decreases the migration energy for oxygen ions, leading to a significant increase in ionic conductivity but at the expense of some electrical conductivity. The electrical and ionic conductivities of La0.3Sr0.7Co0.07Ti0.93O3 - delta are 63 S/cm and 6 x 10(-3) S/cm, respectively, at 700 degrees C. Both La0.3Sr0.7TiO3 - delta and La0.3Sr0.7Co0.07Ti0.93O3 - delta show relatively stable electrical conductivities under oxygen partial pressure of 10(-14)-10(-19) atm at 800 degrees C. These properties make La0.3Sr0.7Co0.07Ti0.93O3 - delta a promising anode candidate for solid oxide fuel cells. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.